Apparatus for drilling



APPARATUS FOR DRILLING Thomas V; Moore, Manhasset, N. Y., assignor toEsso Research and Engineering Company, a corporation of Delaware IApplication October 1, 1951, Serial No. 249,113

1 Claim. (Cl. 255-24) The present invention relates to an apparatus fordrilling well bore holes. In accordance with the present invention anincreased drilling speed is obtained with the aid of jets in which avalve is positioned at the bottom of the drill pipe which opens when apredetermined high pressure is imposed upon it. The valve remains openuntil the pressure falls to a predetermined value. By operating in thismanner the energy intermittently stored in the drill pipe is effectivelyreleased in a pulsing mud jet of very high reaction.

In the exploration for oil the art of drilling well bore holes intosubterranean areas of the earth has been widely investigated andextensively developed. The techniques employed are many and a widevariety of drilling bits and associated apparatus have also beendeveloped. One conventional procedure is to attach a suitable bit on theend of a pipe string and to rotate the bit by the rotation of the pipestring.

Thus, at the present time, the majority of drilling operations areconducted by employing rotary drilling equipment. In conventional rotarydrilling, a hollow jointed steel shaft called the drill stem is rotatedfrom the surface of the earth. This shaft, extending downwardly into theearth to any desired depth, rotates a drill bit. For a number ofpurposes, a weighted fluid called drilling mud is circulated in onedirection through the drill stem and in the opposite direction throughthe annulus between the drill stern and the bore hole.

In drilling operations of this character, it is also known to employrelatively high velocity jets. The jetting action is secured by imposinga pressure on the drilling fluid within the drill stern by means ofsurface equipment. This fluid is jetted through suitable fluid jetpassageways in the bit in order to aid the drilling operation. This typeof jet drilling technique is particularly suitable for securingsatisfactory drilling rates when piercing ditficult rock formations.However, in the conventional jet drilling operation of the characterdisclosed, the efliciency of the system depends upon the reaction of thejets of mud flowing through the water courses. The reaction of the jetsis limited due to frictional loss of energy such as the friction of themud flowing through the long string of drill pipe to the bit. Thisfrictional loss consumes a large part of the energy of the mud streamwhich otherwise could be used in the jetting action. In accordance withthe present invention, a valve is utilized which is disposed at thelower end or bottom of the drill pipe. This valve will open when apredetermined pressure is reached within the drill pipe at which time itwill open and will remain open until the pressure has dropped to apredetermined point, thus producing an effective pulsing motion of thejets.

The present invention may be readily understood by reference to thedrawing illustrating one embodiment of the same. Referring specificallyto the drawing, a drill stem 1 is shown disposed in well bore hole 2,which extends from the surface through subterranean formations 'ice 2 3.Attached to the lower end of drill stem 1 is a fishtail bit 4 containingfluid passageways 6. In normal operation, a drilling fluid is pumpeddown within the drill stem.

This fluid flows through ports 6 either in the bit itself or throughother ports into the annular .area between the bore hole Wall and theouter surface ofvthe drill stemQ In accordance with the presentinvention, this fluid passes through fluid passageway 6 and is jetted ata high velocity in order to increase the drilling rate. In accordancewith the present invention, a suitable piston valve 9 which seats at.the topof conduit 15 or its equivalent is disposed in thelower end ofthe drill stem. The valve assembly is positioned'within the drill stemby a suitable structural means 12 containing ports 14 so as to permitthe passage of downflowing fluid. This valve remains closed until apredetermined high pressure is imposed upon it. The valve opens andremains open until the pressure falls to a predetermined value. Thus,there is secured an intermittent, high velocity pulse jet action throughthe jets 6 which is secured by utilizing the stored energy of the mudstream within the drill stem.

Any suitable type of valve may be employed, as for example a pintle typevalve. The valve preferably operates against the action of a springmeans 16. Thus, for example, as the pressure builds up on the fluid headwithin the drill stem, pressure is exerted against the face of the valveas illustrated by arrows 7. This pressure is exerted against thedownward thrust of a spring means 8 positioned in cylinder 10. As thepressure reaches a predetermined high value, the face of the valve 9moves off valve seat 11 at which time the area of the valve face exposedto the thrust of the mud increases abruptly due to the design of thevalve, thus, materially and rapidly increasing the total force on theface of the valve. The effect of this is to have the valve in effectsnap open rapidly. The entire valve mechanism 9 comprising a pistonelement, moves upwardly in cylinder element 10 against the force ofspring element 8.

As the mud pressure is released after a certain quantity of fluid isjetted through ports 6, the valve starts to close and then snaps backrapidly for the reasons given heretofore. The entire valve assembly isrigidly positioned in the bottom of drill stem 1 by suitable braceelements 12, which brace elements permit the mud fluid to flow freelypast the same. In order to permit satisfactory operation of the valvemechanism and to equalize the effect of the fluid head of mud in thearea between the drill stem and the bore hole with that of the fluidhead of the mud within the drill stem, a port element 13 is providedwhich communicates between the area in the cylinder and the area betweenthe drill stem and the bore hole wall. Thus, the thrust of the fluidhead within the drill stem exerted on the face of valve 9 is equalizedby the thrust of the fluid mud head between the drill stem and the borehole wall exerted through port 13 and on the base of valve 9 in thecylinder. It is also within the concept of the present invention toprovide a mechanical or pneumatic surge tank to store hydraulic energyof the mud in the lower part of the drill pipe.

The present invention is broadly concerned With apparatus for providinga pulsing, jetting action of the fluid from the drill bit. This isprovided by the operation of a mechanical valve which remains closeduntil a predetermined relatively high pressure is reached. At this pointthe valve, due to its design, snaps open thus releasing the storedenergy of the mud through the jets, thus providing a jet action. At apredetermined point, the valve snaps closed and the cycle is repeated.The number of cycles per minute may vary appreciably depending upon theparticular structure being drilled as well as upon other relatedfactors, such as the rotational speed of drilling. A satisfactorydrilling rate is from about 80 to 150, preferably, from about 120 to 140revolutions per minute. Under these conditions, it is desirable to jetthe fluid from about 1 to 10, preferably from about 2 to 5 times perrevolution.

By operating in accordance with the present invention, a pump ofrelatively small horse power may be employed to store hydraulic energyin the drill pipe for a period of time and then cause the energy sostored, to be released in mud jet of very high reaction, which wouldappreciably increase the speed of drilling.

What is claimed is:

In an apparatus for drilling bore holes into subterranean surfaces animproved drill bit assembly which comprises a drill bit attached to thelower end of a pipe string, ports in said bit communicating by means ofa common conduit to within said pipe string, a valve assembly positionedabove said bit and concentrically disposed within said pipe stringcomprising a piston element which seats on a seat formed at the junctureof said conduit and a surface of the bit, and a cylinder element inwhich said piston element slides, said cylindrical element being rigidlypositioned with respect to said pipe string by suitable brace elements,a vent communicating from within said cylindrical element above saidpiston to without said pipe string, a spring means positioned withinsaid cylindrical element so as to exert a downward thrust on the pistonelement so as to seat the piston element in said seat, therebycontrolling the flow of fluid through said conduit, said piston elementbeing characterized by being upwardly flared and extending above saidseat, whereby a predetermined lateral force exerted by the fluid headwithin said pipe string will exert an upward thrust component on saidpiston valve element which will exceed the downward thrust exerted bysaid spring means, whereby said piston element will move upwardly andallow free communication through said common conduit.

References Cited in the file of this patent UNITED STATES PATENTS842,049 Wolski Jan. 22, 1907 1,853,379 Rotinotf Apr. 12, 1932 2,045,368Reed June 23, 1936 2,422,031 Merten June 10, 1947 2,507,585 BassingerMay 16, 1950

